Problem: Rewrite ${\dfrac{5^{-12}}{5^{-9}}}$ in the form ${5^n}$.
Answer: ${ \dfrac{5^{-12}}{5^{-9}} = 5^{-12-(-9)}} $ ${ \hphantom{\dfrac{5^{-12}}{5^{-9}}} = 5^{-3}} $